Magnetization jumps in proximity of an itinerant ferromagnet

Abstract

Placing our system in the proximity of the Stoner instability, the mean-field theory of itinerant metamagnetism and its implications are discussed in this study for several different cases. Two analytically solvable models, namely the M${}^6$ Landau theory and the comprehensive analytical solution derived from the one-dimensional tight-binding density of state with the van Hove singularity (VHS), are presented. In our exploration, we calculate the analytical thermodynamic functionals, construct the phase diagrams, pinpoint the quantum critical endpoints, and delineate the critical magnetic fields. We examine the necessary and sufficient conditions for itinerant metamagnetism, scrutinizing the band structure effects and energy functionals. Finally, we extend the theoretical framework to the metamagnetic compound Sr${}_3$Ru${}_2$O${}_7$ by using an ab initio tight-binding. Our analysis reveals that the VHS plays a pivotal role in inducing metamagnetism in layered ruthenates Sr${}_3$Ru${}_2$O${}_7$. Furthermore, we conduct a comparative analysis, discussing the distinctions between proximity to a ferromagnetic or an altermagnetic phase.